Windows crash in ctime_r()

Windows crash in ctime_r()

[Michael Schoberg (mschoberg)]

I think I found an issue in os\windows\posix.c that results in a FIO crash (on Windows.)  I'm including a patch that resolves the crash for us, but includes another (optional) fix.

Crash issue:  possix.c  - ctime_r() will reference a negative array index on Sunday.  SYSTEMTIME states the days of the week as: "0=Sunday, .. , 6=Saturday."  The "fix" can likely be dialed back to safely assume the days/months will adhere to how they're documented.

Optional - StringCchPrintfA() calls should allow for the string plus a NULL character.  Instead, the value getting passed in is for the entire string size.



os/windows/posix.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/os/windows/posix.c b/os/windows/posix.c
index 41fc480..fd3d9ab 100755
--- a/os/windows/posix.c
+++ b/os/windows/posix.c
@@ -243,12 +243,12 @@ void Time_tToSystemTime(time_t dosTime, SYSTEMTIME *systemTime)
 char* ctime_r(const time_t *t, char *buf)
 {
     SYSTEMTIME systime;
-    const char * const dayOfWeek[] = { "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun" };
+    const char * const dayOfWeek[] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
     const char * const monthOfYear[] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
 
     Time_tToSystemTime(*t, &systime);
     /* We don't know how long `buf` is, but assume it's rounded up from the minimum of 25 to 32 */
-    StringCchPrintfA(buf, 32, "%s %s %d %02d:%02d:%02d %04d", dayOfWeek[systime.wDayOfWeek - 1], monthOfYear[systime.wMonth - 1],
+    StringCchPrintfA(buf, 31, "%s %s %d %02d:%02d:%02d %04d", dayOfWeek[systime.wDayOfWeek % 7], monthOfYear[(systime.wMonth - 1) % 12],
 										 systime.wDay, systime.wHour, systime.wMinute, systime.wSecond, systime.wYear);
     return buf;
 }
@@ -888,7 +888,7 @@ struct dirent *readdir(DIR *dirp)
 
 	if (dirp->find_handle == INVALID_HANDLE_VALUE) {
 		char search_pattern[MAX_PATH];
-		StringCchPrintfA(search_pattern, MAX_PATH, "%s\\*", dirp->dirname);
+		StringCchPrintfA(search_pattern, MAX_PATH-1, "%s\\*", dirp->dirname);
 		dirp->find_handle = FindFirstFileA(search_pattern, &find_data);
 		if (dirp->find_handle == INVALID_HANDLE_VALUE)
 			return NULL;

Re: Windows crash in ctime_r()

[Jens Axboe]

On 05/16/2016 03:50 PM, Michael Schoberg (mschoberg) wrote:
> I think I found an issue in os\windows\posix.c that results in a FIO
> crash (on Windows.)  I'm including a patch that resolves the crash for
> us, but includes another (optional) fix.  > > Crash issue:  possix.c  -
> ctime_r() will reference a negative array index on Sunday.  SYSTEMTIME
> states the days of the week as: "0=Sunday, .. , 6=Saturday."  The "fix"
> can likely be dialed back to safely assume the days/months will adhere
> to how they're documented.
>
>
> Optional - StringCchPrintfA() calls should allow for the string plus a
> NULL character.  Instead, the value getting passed in is for the entire
> string size.

Thanks, both look good, applied.

-- 
Jens Axboe